I am of the opinion that raising a pull request (which is a kind of branch) off main, then getting review, approval and a merge within an hour counts as trunk b

I am of the opinion that raising a pull request (which is a kind of branch) off main, then getting review, approval and a merge within an hour counts as trunk based development. But if there are long-lived branches, or a "release branch" which means that main is not what is deployed to production, or that main/"the trunk" is not what is merged onto, then you are definitely not doing trunk based development.